<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta http-equiv="X-UA-Compatible" content="IE=edge" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Document</title>
  </head>
  <body>
    <script>
      if (true) {
        // 局部变量
        const username = 'jack';
        console.log('hello', username);
      }
      // console.log('hello', username);
      function say() {
        const username = 'lili';
        console.log('hi', username);
      }

      for (let i = 0; i < 10; i++) {
        console.log(i);
      }

      // {
      //   let i = 0;
      //   console.log(i);
      // }

      // {
      //   let i = 1;
      //   console.log(i);
      // }

      // {
      //   let i = 2;
      //   console.log(i);
      // }

      //...
    </script>
  </body>
</html>
